Article Figures & Data

Figures

Effect of exemestane and tamoxifen on the growth of MCF-7 aromatase tumor xenografts in ovariectomized athymic mice. All animals were inoculated with MCF-7Ca aromatase-transfected human breast cancer cells at two sites per flank and supplemented with androstenedione (δ4A, 100 μg/d) for the duration of experiment. When tumor volumes reached ∼500 mm3, animals were grouped (n = 5) for treatment with vehicle, tamoxifen (100 μg/d), and exemestane at different doses (100 and 250 μg/d). Tumor volumes were measured weekly and expressed as the percentage change from their initial tumor volume (18).

Effect of letrozole (10 μg/d) and fulvestrant (1 mg/d) alone or the combination on the growth of MCF-7 aromatase tumor xenografts in female ovariectomized athymic nude mice. Animals were inoculated with MCF-7Ca cells at one site on each flank and were supplemented with androstenedione (100 μg/d) for the duration of experiment. When tumors reached ∼300 mm3, animals were divided into four groups and injected s.c. daily with vehicle (control; n = 6), fulvestrant (1 mg/d; n = 7), letrozole (10 μg/d; n = 18), or letrozole (10 μg/d) plus fulvestrant (1 mg/d; n = 5). Tumor volumes were measured weekly and expressed as the percentage change in mean tumor volume relative to the initial size at week 0. At week 7, all treatments were significantly better in suppressing tumor growth compared with the control animals (P < 0.001), which were sacrificed due to the large tumor size. At week 17, letrozole was superior to fulvestrant in controlling tumor growth (P < 0.001). In addition, treatment with letrozole plus fulvestrant was superior to fulvestrant alone (P < 0.001). Fulvestrant-treated mice were sacrificed at week 17 due to large tumor size. At week 29, letrozole (10 μg/d) was less effective than letrozole plus fulvestrant in controlling tumor growth (P = 0.0005). In addition, tumor volumes were statistically significantly larger in the letrozole treatment group than in the combination (P < 0.0001).